Long persistence display screen supplement to crt

ABSTRACT

A long persistence display screen that can be utilized with any conventional cathode ray tube is disclosed. The long persistence display screen of this invention comprises a translucent or transparent base material such as mylar that has been suitably impregnated with an appropriate phosphor material. This semiflexible screen is placed in intimate contact with the cathode ray tube with which it is utilized. Any rapidly traced wave form, or the like, illuminated on the cathode ray tube will be visible on the screen of this invention for a longer period of time due to the action of the afterglow in the phosphor used in the screen.

United States Patent [191 Reiser et al.

[ LONG PERSISTENCE DISPLAY SCREEN SUPPLEMENT TO CRT [76] Inventors:Donald Reiser, 5647 Ravenel Ln.,

Springfield, Va. 22151; Ralph Belcher, 10603 Lorain Ave., Silver Spring,Md. 20901 [22] Filed: Dec. 3, 1973 21 Appl. No.: 421,042

OTHER PUBLICATIONS R. B. Johnson High Resolution Image Buffer SystemJuly 22, 1975 2-72, IBM Technical Disclosure Bulletin, Vol-l4 No. 9.

Primary Examiner-Robert L. Richardson Assistant ExaminerEdward L. ColesAttorney, Agent, or FirmWitherspoon and Lane [57] ABSTRACT A longpersistence display screen that can be utilized with any conventionalcathode ray tube is disclosed. The long persistence display screen ofthis invention comprises a translucent or transparent base material suchas mylar that has been suitably impregnated with an appropriate phosphormaterial. This semi-flexible screen is placed in intimate contact withthe cathode ray tube with which it is utilized. Any rapidly traced waveform, or the like, illuminated on the cathode ray tube will be visibleon the screen of this invention for a longer period of time due to theaction of the afterglow in the phosphor used in the screen.

11 Claims, 4 Drawing Figures LONG PERSISTENCE DISPLAY SCREEN SUPPLEMENTTO CRT The invention described herein may be manufactured, used, andlicensed by or for the Government for Governmental purposes without thepayment to me of any royalties thereon.

BACKGROUND OF THE INVENTION This invention relates to display screens,and more particularly to long persistence display screens utilized assupplements to a cathode ray tube.

A given display or trace on a conventional cathode ray tube has a shortpersistence unless, of course, the trace or display is repeated over andover again. It is known in the art that certain phosphors, when excited,exhibit a long persistence and various devices utilizing this fact areknown in the art. However, these devices are all specially built toserve a particular need. None of these prior art, specially builtdevices can be readily used with any conventional cathode ray tube.Thus, a need exists for a device that can be utilized as a supplement toany cathode ray tube to provide a long persistence display.

Such a device can be used to provide a long persistence display with anycathode ray tube either of the lab or TV type and will, of course, havea large number of applications. For example, a long persistence screendesigned in accordance with this invention can be used to provide ameans for longer term storage of, for example, data transmitted by anyconventional means and can be used to provide a means of converting astandard lab oscilloscope to an oscilloscope having a long-term storagecapability approaching the display time characteristics of a storagetube display unit. As will be apparent later, there are, of course, manyother uses for a long persistence display screen constructed inaccordance with this invention.

SUMMARY OF THE INVENTION The long persistence display screen of thisinvention comprises a base material such as mylar that has been suitablyimpregnated with an appropriate phosphor or phosphors, as the case maybe. The semi-flexible screen impregnated with the phosphor is placed onthe face of a conventional cathode ray tube. Any rapidly traced waveform illuminated on the cathode ray tube will be visible for a longerperiod of time on the screen of this invention. Since the screen is madeof mylar, or the like, it is flexible or at least semi-flexible andtherefore can be readily placed on the face of a cathode ray tube.Further, it can be removed and utilized with still another cathode raytube. Thus, screens constructed in accordance with this invention can beutilized with any cathode ray tube. One merely secures the screen to theface of the cathode ray tube by any suitable means. In fact, the screenitself could be coated with a transparent, tacky material so that itwould adhere to the face of the cathode ray tube without any separatesecuring means. Or, an adhesive could be placed along the border of thescreen.

It is therefore an object of this invention to provide a longpersistence display screen.

It is another object of this invention to provide a long persistencedisplay screen used as a supplement to a conventional cathode ray tube.

It is still another object of this invention to provide a flexible, longpersistence display screen.

It is a further object of this invention to provide a flexible, longpersistence display screen that can be utilized with any conventionalcathode ray tube It is still a further object of this invention toprovide a long persistence display screen that can be readily attachedto and removed from the face plate of a conventional cathode ray tube.

BRIEF DESCRIPTION OF THE DRAWING The above-mentioned and other objectsof the invention will become readily apparent from the followingdetailed description when read in conjunction with the annexed drawingin which:

FIG. 1 is a pictorial view showing a display screen constructed inaccordance with this invention;

FIG. 2 is a cross-sectional view of a display screen constructed inacccordance with this invention;

FIG. 3 is a side view of a conventional cathode ray tube showing thescreen of this invention in intimate contact with the face plate of thecathode ray tube; and

FIG. 4 is a front view of a cathode ray tube with the screen of thisinvention in intimate contact with the face plate of the cathode raytube.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a pictorial view of thedisplay screen 1 constructed in accordance with this invention. As moreclearly shown in FIG. 2, the screen 1 consists of a base material thathas been impregnated with a phosphor or phosphors 2.

When screen 1 is excited, phosphor 2 will provide an afterglow inresponse to the excitation. The length of time that this afterglowpersists depends upon the type of phosphor utilized. Thus, by selectinga particular phosphor for phosphor 2 various different phosphorescenttimes can be obtained. Phosphors, both organic or inorganic, exhibitinga whole range of phosphorescent time in response to excitation are knownin the art. For example, the inorganic phosphors are of the Zns, CdS, orZnSzCdS class activated with Ag, Cu, Mg, Mn, etc. These phosphorsprovide a phosphorescent lifetime of from a few milliseconds to hours.The organic types usually have conjugated double hands and closed cyclicring configurations. The specific or particular phosphor or phosphorsused for phosphor 2 is not critical to this invention. Any suitablephosphor or phosphors that provide the desired persistence time can beutilized. It is, of course, true that this invention basically relatesto long persistence display screens and therefore only those phosphorsthat provide sufficiently useable long persistence times would normallybe utilized. However, in some cases a persistence of but severalmilliseconds may be sufficiently long for that particular application.In other words, screens designed in accordance with this invention canbe designed to have specific controlled persistence times. The times canrange from several milliseconds to hours.

The screen, as shown in FIG. 1, is generally rectangular shaped. Thescreen can take on any desired shape. Since the screens are intended foruse with conventional cathode ray tubes they will be either rectangularshaped or circular since cathode ray tubes are generally eitherrectangular or circular shaped. It is, of course, true that a circularor rectangular screen of sufficient size can be used with either acircular or rectangular cathode ray tube. Since screen 1 issemi-flexible, it can be made into a continuous sheet rather than anindividual screen and the sheet can be cut to any desired size toprovide an individual screen from the long sheet. This sheet can befolded or rolled up for convenient storage.

FIG. 3 shows screen 1 as it is utilized with a conventional cathode raytube 3. As shown in FIG. 3, screen 1 is placed in intimate contact withthe face plate 5 of cathode ray tube 3. Screen 1 can be secured to faceplate 5 by any suitable means. For example, screen 1 can be taped ontothe face plate of cathode ray tube 3, or a border of adhesive can beprovided around the edges of screen 1, or screen 1 can have coatedthereon a transparent adhesive so that the entire screen will readilyadhere to face plate 5. Screen 1 is to be removably secured to faceplate 5 so that it can be readily removed from the face plate after useand again utilized with either cathode ray tube 3 or any other cathoderay tube. In other words, it is intended that screen 1 be readilyapplied to and removed from face plate 5 of cathode ray tube 3. FIG. 4is merely a front view of cathode ray tube of FIG. 3 and shows screen 1in intimate contact with face plate 5.

After screen 1 has been secured to face plate 5, any trace that appearsacross the screen of cathode ray tube 3 will excite the phosphor inscreen 1. Therefore, screen 1 will phosphoresce or glow in the excitedareas and thereby provide a replica of the trace that appeared acrossthe screen of the cathode ray tube. Since the phosphor used in screen 1provides a long persistence, the trace of afterglow will remain onscreen 1 long afterthe trace has disappeared on the screen of thecathode ray tube. In this manner, any trace or data can be studied for aperiod of time longer than that which would be normally provided withthe cathode ray tube itself. By placing screen 1 across the face plateof the cathode ray tube, any data will remain for a much longer periodof time and can, therefore, be analyzed and studied by the observer. Inaddition to providing long persistence for data, screen 1 has thecapability of providing a means for converting a standard laboratoryoscilloscope to an oscilloscope having a long term storage capabilityapproaching that of the display time characteristics of a storage tubedisplay unit. In other words, by means of screen 1, any conventionalcathode ray tube can be converted to one having a long term storagecapability. Screen 1 can be used with any conventional cathode ray tubeand can be readily applied to or removed from the face plate of thecathode ray tube. Thus, this invention provides a long term storagecapability with conventional cathode ray tubes that heretofore has notbeen available in the art.

While'the invention has been described with reference to a particularembodiment, it will be obvious to those skilled in the art that variouschanges and modifications can be made to the embodiment disclosedwithout departing from the spirit and scope of the invention as setforth in the appended claims.

What is claimed is:

1. A long persistence display screen supplement for a cathode ray tubecomprising:

a flexible binder, and

phosphor impregnated into said flexible binder.

2. A long persistence display screen as described in claim 1 whereinsaid flexible binder is made from a material selected from the family ofmaterials known as silastics.

3. A long persistence display screen as described in claim 1 whereinsaid flexible binder is mylar.

4. A long persistence display screen as defined in claim 3 wherein saidphosphor is Zns activated with one of the elements selected from thegroup consisting of Ag, Cu, Mg, and Mn.

5. A long persistence display screen as defined in claim 2 wherein saidphosphor is CdS activated by one of the elements selected from the groupconsisting of Ag, Cu, Mg, and Mn.

6. A long persistence display screen as defined in claim 2 wherein saidphosphor is ZnS:CdS activated with one of the elements selected from thegroup consisting of Ag, Cu, Mg, and Mn.

7. A long persistence display system comprising:

a cathode ray tube; and

a flexible screen comprising a flexible binder impregnated with a longpersistence phosphor, said flexible screen being placed directly on theoutside of the face plate of said cathode ray tube.

8. A long persistence display system as defined in claim 7 wherein saidlong persistence phosphor is ZnS activated with one of the elementsselected from the group consisting of Ag, Cu, Mg, and Mn.

9. A long persistence display system as defined in claim 7 wherein saidlong persistence phosphor is CdS activated by one of the elementsselected from the group consisting of Ag, Cu, Mg and Mn.

10. A long persistence display system as defined in claim 7 wherein saidlong persistence phosphor is ZnS:CdS activated with one of the elementsselected from the group consisting of Ag, Cu, Mg and Mn.

11. A method for providing a long persistence display with aconventional cathode ray tube having a short persistence time comprisingthe steps of:

l. placing a flexible long persistence screen directly on the outside ofthe face plate of a cathode ray tube;

2. providing a trace across the screen of the cathode ray tube;

3. exciting the phosphor of said flexible screen from said trace acrossthe screen of said cathode ray tube to provide a duplicate of saidtrace; and

4. removing said trace from said cathode ray tube.

1. placing a flexible long persistence screen directly on the outside ofthe face plate of a cathode ray tube;
 1. A long persistence displayscreen supplement for a cathode ray tube comprising: a flexible binder,and phosphor impregnated into said flexible binder.
 2. A longpersistence display screen as described in claim 1 wherein said flexiblebinder is made from a material selected from the family of materialsknown as silastics.
 2. providing a trace across the screen of thecathode ray tube;
 3. A long persistence display screen as described inclaim 1 wherein said flexible binder is mylar.
 3. exciting the phosphorof said flexible screen from said trace across the screen of saidcathode ray tube to provide a duplicate of said trace; and
 4. removingsaid trace from said cathode ray tube.
 4. A long persistence displayscreen as defined in claim 3 wherein said phosphor is Zns activated withone of the elements selected from the group consisting of Ag, Cu, Mg,and Mn.
 5. A long persistence display screen as defined in claim 2wherein said phosphor is CdS activated by one of the elements selectedfrom the group consisting of Ag, Cu, Mg, and Mn.
 6. A long persistencedisplay screen as defined in claim 2 wherein said phosphor is ZnS:CdSactivated with one of the elements selected from the group consisting ofAg, Cu, Mg, and Mn.
 7. A LONG PERSISTENCE DISPLAY SYSTEM COMPRISING: ACATHODE RAY TUBE, AND A FLEXIBLE SCREEN COMPRISING A FLEXIBLE BUNDERIMPREGINATED WITH ALONG PERSISTENCE PHOSPHOR, SAID FLEXIBLE SCREEN BEINGPLACED DIRECTLY ON THE OUTSIDE OF THE FACE PLATE OF SAID CATHODE RAYTUBE.
 8. A long persistence display system as defined in claim 7 whereinsaid long persistence phosphor is ZnS activated with one of the elementsselected from the group consisting of Ag, Cu, Mg, and Mn.
 9. A longpersistence display system as defined in claim 7 wherein said longpersistence phosphor is CdS activated by one of the elements selectedfrom the group consisting of Ag, Cu, Mg and Mn.
 10. A long persistencedisplay system as defined in claim 7 wherein said long persistencephosphor is ZnS:CdS activated with one of the elements selected from thegroup consisting of Ag, Cu, Mg and Mn.
 11. A method for providing a longpersistence display with a conventional cathode ray tube having a shortpersistence time comprising the steps of: